I liked this project because I got to use 3D printing “just for fun” and not simply for the purpose of a prototype. I used Thingiverse to look for an impossible object that I could do, and I decided on this snake. It is impossible because the interlocking parts couldn’t be made with traditional methods.

FDM and SLA printing were the two methods I chose because they were easily accessible at the OEDK (basically the only two options). I have used FDM many times before, and I used to think it was the only type of 3D printing there was (glad this class has introduced me to more). Though my object had the potential to be flexible, I made sure to be aware of the gumball capsule constraints (1.85 inches wide and 2 inches tall) as I did a test piece.

When I imported the file into the slicer, its size (oriented in a spiral) was 4.039 inches across, so I scaled it down by half. As you can see above, that size print only took up the bottom of the capsule, and we were tasked to fill as much space as possible. I did another estimate print at 80% of the original size (3.23 inches across), and I liked how this print filled the space and settled on that size for the additional objects using FDM. Also, while figuring out the size, I used the Bambu printers to speed up my prints.

Next up was the resin printing. I have never done resin printing before, but it was a straightforward, albeit time-consuming process. I attempted to start my resin print one night, only to come back the next day and have it not printed. It turns out that there wasn’t enough resin to complete the piece. The original resin I was going to use was Tough 1500 but since that was out of stock, I switched to Flexible 80A. There was no reasoning behind these choices, I was just going with what the machine was loaded with. In hindsight, the Tough 1500 might have been the best for me to use, but we will get to that part soon. Also, It is so cool, that the machine knows what to do with each material that can be put into it.

 

I left the printer to run and came back to the OEDK to see that it was successful! I made sure to read the instructions, and I carefully removed my pieces from the build platform.

After removing them, I put them through 2 10-minute washes and then started removing the supports. I wanted to remove the supports before I cured the snakes, just in case they were hard to take off and my pieces got damaged (more on that later too). This process took a good bit of time because of how many supports there were. When that was finally done, I put them in the machine to cure.

The snakes were less glossy when they came out but still very transparent. Now when I went to try and bend the snakes, I realized that they weren’t exhibiting a full range of motion. Then, I saw the internal supports that each piece had on it. Cutting these off took even longer since I had to be delicate, and these supports were harder to reach. I did my first snake with no problem and tested its movement along the table to make sure it was moving properly. However, on my second snake things took a turn.

My snake had broken into 3 pieces, and so did my heart. I did not want to reprint it and waste resin, so I decided to try and do a patch job. I looked at the glue sheet but didn’t see anything specific to resin, so I went with superglue. To my dismay, it didn’t stick. My next choice was hot glue, which was successful on one of the links. However, on the link where I tried superglue first, it would not stick. My last resort was a needle and thread.

On my first attempt, I broke one of the links more because the section was too thin for the needle. I adjusted my method and went through the thicker part of the link and was able to successfully loop the thread through and connect the snake back together. Though the movement is a little stiffer in that area, at least it is still able to move as a whole. After talking to Dr. Wettergreen, I determined that SLA printing is not the best method for a piece with interlocking parts. He suggested different methods like SLS and Carbon Fiber FDM, but unfortunately, they weren’t accessible, and I finished with my 3 FDM and 2 SLA snakes!

Cost Analysis:

• Labor (15/hr): 4 hours of work = $60
• Capsules: From Amazon: 150 capsules for $30 so $0.20 each and I used 5 = $1
• Filament: Bambu PLA, $27.99 per kg, and I used about 20 grams per snake = $0.06
• Resin: FormLabs Flexible 80A, $199 per liter, and used about 20 mL per snake = $8
  • Unfortunately, I didn’t note how much filament/resin I used, so I estimated (using Sarah’s worm)

Clean Workspace (sorry no picture): After removing supports from my PLA snakes in the Computer Lab, I made sure to wipe up all of the little pieces. After putting my resin snakes to wash, I made sure to clean the build plate with isopropyl alcohol and put it back. I also cleaned all the tools I used to remove the print and its supports. After cutting supports and preparing my piece, I made sure to remove all items that I used and put them back in their respective spots.